He was taken to hospital and diagnosed with bleeding on the brain, a fractured cheekbone and facial grazing. Hamer, aged 38, of Albion Street, Bolton has pleaded not guilty to inflicting grievous bodily harm.

The court heard the incident took place on a busy afternoon in Manchester city centre and was witnessed by Hamer's two female colleagues as well as shocked passers-by, many of who became hostile towards the police officers.

Andrew Ford, prosecuting, told the jury that on Saturday afternoon July 28, 2012, police officers were called to Starbuck's in Market Street by staff because a drunk Mr Bradbury was smoking in the toilets.

Hamer arrested him for a public order offence, handcuffed him and brought him out of the premises.

His two female colleagues waited with him while Hamer went back inside to talk to witnesses.

Hamer told the jury that when he came back out of Starbucks Mr Bradbury kept asking why he had been arrested and that he “became more aggressive towards me”.

He took him into the quieter Tibb Street as the street outside Starbucks was crowded.

Hamer added: “I decided that for my safety and control I wanted to place him on the floor.”

Hamer, who was diagnosed with MS in November, 2012, and who is on restricted police duties, added he shouted to his colleagues to get an ambulance and knelt down to take the handcuffs off and placed Mr Bradbury in the recovery position.